<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      /* 权重 0 继承 NULL  0权重和无权重是不同的，0>NULL*/
      html {
        color: red;
      }
      /* 权重 0001 继承 NULL 0>NULL*/

      h2 {
        color: blue;
      }
    </style>
  </head>
  <body>
    <article>
      <h2>hdcms <span>内容管理系统</span></h2>
    </article>
  </body>
</html>
